JB 10046-1999 Limits and measurement methods for machine tool electrical noise
Some standard content:
ICS29.120
Standard of the Machinery Industry of the People's Republic of China
JB10046-1999
Limits and determination methods of noise of electrical appliances for machine toolsPublished on October 8, 1999
National Bureau of Machinery Industry
Implementation on March 1, 2000
JB10046-1999
This standard is a revision of ZBK30002-90 "Limits and determination methods of noise of electrical appliances for machine tools". Compared with ZBK30002-90, the main technical contents of this standard have been changed as follows: the scope of application has been expanded. The rated current of the contactor in the previous version of the standard has been increased to 80A. At present, the contactor production in the industry has reached 630A. Therefore, the "small capacity contactor" in the previous version of the standard has been revised to "electromechanical contactor", and the upper limit of the rated current has been cancelled. The "motor starter" category of products has been added to the scope of application of this standard. This standard changes "traction electromagnet" to "AC electromagnet"; modifies the noise limit values of some products: deletes the inappropriate parts of the measurement method, and refines the retained parts so that they can be understood without consulting other standards. At the same time, clarifies the conventional measurement methods.
This standard replaces ZBK30002-90 from the date of implementation. Appendix A of this standard is the appendix of the standard.
Appendix B and Appendix C of this standard are both prompt appendices. This standard is proposed and managed by Chengdu Machine Tool Electrical Equipment Research Institute. The responsible drafting units of this standard: Tianjin Second Machine Tool Electrical Equipment Factory, Zhejiang Yaohua Group Corporation. The main drafters of this standard: Tong Li, He Jianguo, He Jianrong, Hao Zhongjing. 1
Mechanical Industry Standard of the People's Republic of China
Limits and measurement methods for noise of machine tool electrical equipment This standard specifies the limit values and measurement methods of noise sound power levels in normal operation of machine tool electrical equipment. JB10046-1999
Replaces ZBK30002--90
This standard applies to electromechanical contactors, motor starters, contactor relays and AC electromagnets (hereinafter referred to as electrical appliances) with an AC frequency of 50Hz or 60Hz and a rated working voltage of 660V or less. When the electromagnetic system of a single electrical appliance is in a normally closed state, the limit value and measurement method of noise.
This standard does not apply to the limit value and measurement of impact noise generated when the electromagnetic system of an electrical appliance is closed or released. 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest version of the following standards. GB/T2900.1—1992
GB/T2900.18—1992
GB/T3102.7—1993
GB/T3238—1982
GB/T 3785-1983
GB/T 39471996
GB/T5226.1-1996
GB/T14048.1—1993
Electrical equipment noise limit values
Electrical T terms Basic terms
Electrical terms Low voltage electrical appliances
Acoustic quantities and units
Acoustic quantity levels and reference values
Electrical and acoustic performance and test methods of sound level meters Acoustic terms and terminology
Industrial machinery and electrical equipment Part 1: General technical conditions Low voltage switchgear and control equipment General provisions
Electrical equipment noise limit values have been specified in their individual products and their values are less than the limit values in Table 1, and can be specified in product standards. 3.1
Those not clearly specified in product standards shall be implemented in accordance with Table 1 unless otherwise agreed upon by the supply and demand parties. Table 1 "Electrical equipment noise limit values
Product name
Electromechanical contactor
Motor starter
Contactor relay
AC electromagnet
Product specification
1,≤63A
≤63A
Full series
Full series
Noise limit values
The acoustic terms, quantities and units used in this standard are in accordance with the provisions of GB/T3947, GB/T3102.7 and GB/T3238
Approved by the State Machinery Industry Bureau on October 8, 1999 and implemented on March 1, 2000
JB10046-1999
3.3 The electrical terms used in this standard are in accordance with GB/T 2900.1, GB/T2900.18, GB/T5226.1 and GB/T14048.1.
4. Noise test environment
4.1 Test environment suitable for electrical type test or periodic test: a) Anechoic chamber;
b) Semi-anechoic chamber.
4.2 Test environment suitable for routine testing of electrical appliances; a) A relatively quiet test room;
b) A relatively quiet production workshop.
4.3 Requirements for anechoic chambers and semi-anechoic chambers
Anechoic chambers or semi-anechoic chambers should be large enough and have high sound absorption so that all frequency bands and selected measurement surfaces have a suitable free sound field within the test frequency range. The principles of anechoic chamber design can be found in Appendix B (Suggested Appendix). 4.3.1 Anechoic chamber The sound pressure level of the background noise in the semi-anechoic room should be less than 34dB. 4.3.2
The volume of the anechoic room or semi-anechoic room should be greater than 200 times the volume of the appliance under test. 4.3.3 According to the operating conditions of the appliance under test, adjust the temperature and relative humidity of the anechoic room or semi-anechoic room, and keep them as constant as possible. 5 Test instruments
5.1 Sound level meter
The sound level meter used should comply with the relevant provisions of Type 1 sound level meter in GB/T3785. 5.2 Microphone and its connecting cable
The microphone used for measurement should be a condenser microphone with good accuracy and stability and a flat frequency response within the test frequency range at the angle of incidence specified by the manufacturer. It is recommended to use a 12mm measurement microphone. The microphone and its connecting cable should be appropriately selected so that the sensitivity does not vary with the measurement. The measurement process changes with temperature. If the microphone is to be moved, great care should be taken to avoid acoustic noise (such as wind noise) or electrical noise (such as caused by gears, flexible cables or sliding contact) that may interfere with the measurement.
5.3 Calibration
Before each measurement, the entire measurement system shall be calibrated at one or several frequencies within the test frequency range using a sound level calibrator with an accuracy of ±0.2dB. The calibrator shall be checked once a year to prove that its output remains unchanged. In addition, the instrument system shall be electrically calibrated regularly over the entire test frequency range, at least once every two years. 6 Electrical Installation and OperationbZxz.net
Electrical installation shall be carried out in accordance with the installation conditions specified in the specific product standards. If there are no clear provisions in the product standards, a typical installation condition shall be simulated as much as practical. 6.1 Installation Method
Many electrical appliances, although they do not radiate strong low-frequency sound themselves, can significantly increase low-frequency sound if the installation method is improper, so that the vibration energy is transmitted to an area large enough to become an effective radiator. If possible, elastic pads should be inserted between the appliance to be tested and the support surface to reduce the vibration transmitted to the support and the reaction to the sound source. However, such elastic pads should not be used if the appliance to be tested is not elastically mounted during typical field operation. 6.2 Auxiliary equipment
JB10046-1999
Careful measures should be taken to ensure that any electrical conduits and lines connected to the appliance do not radiate significant sound energy into the test room. All auxiliary equipment should be placed outside the test room as far as practicable, and all objects in the test room should be removed so as not to affect the measurement. 6.3 Electrical operation
The electromagnetic coil of the appliance is in a cold state, and the rated control power supply voltage is applied. The contact circuits of the electromechanical contactor, motor starter, and contactor relay are not energized: the brake electromagnet is loaded in the manner specified in the product standard. After the electromagnetic system of the appliance is in a stable closed state, the noise is measured. The control power supply voltage fluctuation range, frequency and other parameters are specified by the product standard. Determination method
To determine the sound power of a sound source, first measure the surface sound pressure level on the hypothetical spherical or hemispherical measurement surface of the sound source, and then calculate the sound power level radiated by the sound source.
7.1 Measurement surface
When measuring in an anechoic chamber or semi-anechoic chamber, the center of the hypothetical sphere or hemispherical surface used to determine the surface sound pressure value should be located at the center of the measured electrical appliance. The radius of the measuring sphere should be equal to or greater than twice the main dimensions of the measured electrical appliance and not less than 1m (if the measuring distance is specified in the product standard, it shall be implemented in accordance with the product standard). 7.2 Measurement points
Measurement in an anechoic chamber, with 6 measurement points. The measurement points are distributed at the intersection of the imaginary sphere and the X, Y, and Z axes (i.e., the radius from the front, back, left, right, top, and bottom of the measured electrical appliance). Measurement in a semi-anechoic chamber, with 5 measurement points, the distribution of measurement points is shown in Appendix A (Standard Appendix) 7.3 Measurement
The microphone used for measurement should be facing the measured electrical appliance. When the noise is stable, the "slow" time counting feature of the sound level meter can be used for measurement. The sound level reading is the average value of the needle swing during the observation period. 7.4. Correction of background noise
When the electrical appliance is not working, measure the background noise sound pressure level. When the difference between the background noise sound pressure level at each measurement point and the sound pressure level when the electrical appliance is working is less than 6dB, the measurement is invalid: the influence of background noise on the sound pressure level of the measurement frequency band should be corrected according to Table 2. Table 2 Correction of background noise sound pressure level
Difference between the sound pressure level measured when appliance 1 is in operation and the background noise sound pressure level 6
Correction value to be subtracted from the sound pressure level measured when appliance I is in operation 1.3
7.5 Calculation of surface sound pressure level
Calculate the surface sound pressure level according to formula (1):
Where: L. - — surface sound pressure level, dB;
JB10046-1999
L,=101g
L—frequency band sound pressure level measured at the i-th point and corrected, dB; N—number of measuring points.
7.6 Calculation of sound power level
According to formula (2), the sound power level is obtained as follows:
Lw=L,+101
Wherein: Lw—noise sound power level, dB; L. is the surface sound pressure level on the measuring sphere, dB; S,-the area of the measuring sphere with radius r (S,=4 in the anechoic chamber; S,=2Tr in the semi-anechoic chamber), m2; S. =lm';
C—temperature and air pressure correction value, dB.
When the test environment conditions are temperature 1 (℃) and atmospheric pressure p. (kPa), the correction value C is: 293Po
C=-10lgl
V273+t100
Note: The sound power level calculated using the A-weighted network in the instrument system is the A sound power level. dB(A). 7.7 Routine inspection
Routine inspection of electrical noise is conducted by monitoring or vibration method. Monitoring method: The inspector listens with his ears to see if the electrical noise exceeds the specified value. If there is any objection, a sound level meter is used to measure it. ()
Vibration method: The inspector simulates the vibration of the electrical appliance with his hands to determine whether the electrical noise exceeds the specified value. If there is any objection, a sound level meter is used to measure it.
Records and reports
The records and reports of electrical noise tests are applicable to the type test and periodic test of electrical appliances and the judgment when there is an objection in routine tests. 8.1 Record items
a) Description of the electrical appliance under test: name, model, specifications, main parameters, manufacturer, date and number of production, sampling quantity, test number, working conditions during measurement, installation method, load value, etc.; b) Measurement conditions: acoustic environment, measurement method, measuring instrument, measurement point layout, readings for each measurement, etc.; C) Others: meteorological conditions, measurement unit or department, measurer, measurement date, location, etc. 8.2 Measurement report
List the measurement data in a chart, calculate the working distance (specify the test distance) and L, and obtain the electrical noise value. Compare it with the standard requirements to make a conclusion on whether the electrical noise value is qualified or not.
JB10046-1999
Appendix A
(Appendix of the standard)
Measurement point layout diagram of semi-anechoic chamber
A1 The hemispherical area S of the measurement surface is calculated according to formula (A1): S=2r
A2 There are 5 measurement points, and the positions and coordinates of the measurement points are shown in Figure A1. Measurement surface
Electrical reference body
L, L, L are the length, width and height of the electrical reference respectively. Figure A] Point positions of hemispherical measurement surface
B1 Overview
JB100461999
Appendix B
(Suggestive Appendix)
Principles of anechoic chamber design
To achieve free field conditions, the test room should have: a) sufficient volume;
b) large sound absorption on the interface within the test frequency range; c) no reflective surfaces and obstacles except those related to the sound source to be measured (including reflective planes, if any); d) sufficiently low background noise level.
B2 Volume of the test room
The requirements for the volume of the test room have been given in 4.3.2. NOTES
1 The volume of the test chamber should be large enough to allow the microphone to be placed in the far field of the sound source being measured without being too close to the sound absorbing surfaces of the test chamber. 2 In the absence of specified data, the far field may be assumed to start at a distance of 2α from the sound source, where a is a conservative value for the largest source size. The measurement surface should be at least A/4 from the sound absorbing surface of the test chamber, where A is the wavelength of the sound wave corresponding to the center frequency of the lowest test band. 3 If the selection of the measurement surface in the test chamber is difficult, rotation and movement of the sound source in the test chamber is allowed during the test series as long as the microphone is always in the far field of the sound source and is not less than A/4 from the sound absorbing surface of the test chamber. B3 Sound absorption of the test seat
The vertical incident energy absorption coefficient of the wall and ceiling treatments shall be equal to or greater than 0.99 measured in a plane wave standing wave tube within the test frequency range. The sound absorption treatment shall be evenly distributed over the entire surface. In an anechoic chamber, the floor should be treated with the same sound absorption as the walls and ceiling. In a semi-anechoic chamber, the floor should be a hard, smooth surface with a vertical incident energy absorption coefficient of no more than 0.06 within the test frequency range. B4 Sound absorption treatment
Satisfactory surface sound absorption treatment is a wedge made of sound absorbing material. The sound absorbing wedge should be tested in advance and the vertical incident sound absorption coefficient within the test frequency range should be greater than 0.99. Sometimes a small cavity can be left behind the wedge, and the length of the cavity is determined by experiment. In general, the total thickness of the sound absorption treatment (wedge plus cavity) should be greater than λ/4, where λ is the sound wavelength corresponding to the center frequency of the lowest frequency band tested. B5 Unwanted reflections
Reflections may occur from pipes, pillars, grids, metal fabrics, cables or various brackets. All objects and instruments should be placed outdoors except those required in the test room. Hollow pipes should be blocked or filled with sound absorbing materials to avoid resonance. B6 Suspended floor construction
Typical floor construction can be used in anechoic chambers, consisting of a grid of stainless steel bars. The bars are less than 2.5 mm in diameter and spaced 2 to 5 cm apart. B7 Background noise
The problem of background noise is usually most severe at low frequencies. To make satisfactory measurements at low frequencies, it is necessary to enclose the anechoic chamber with massive walls and place the entire structure on vibration isolators. At high frequencies, electrical noise may interfere. Air absorption
In anechoic chambers (volume size 200m\), corrections for room air absorption may be required at high frequencies. JB 10046--1999
Appendix C
(Indicative Appendix)
Common Acoustic Terms
This appendix extracts 17 common acoustic terms in GB/T3947. The numbers in parentheses are the corresponding clauses in GB/T3947, and the words in square brackets can be omitted. C1 Noise (1.11) noise
a) Disordered, intermittent or statistically random acoustic oscillations; b) Unwanted sound. It can be extended to any unwanted interference in a certain frequency band, such as radio wave interference. C2 Background noise (1.16)
backgroundnoise
All interference that is not related to the presence or absence of signals in the system that generates, inspects, measures or records. C3 Sound pressure (1.19)
soundpressure
The difference between the pressure in the medium and the static pressure when there is a sound wave, in Pascal, Pa. soundpowerofasource
C4 Sound power (1.28)
Sound power is the total energy emitted by the sound source per unit time. soundpressurelevel
C5 Sound pressure level (1.24)
The logarithm of the ratio of the sound pressure to the reference sound pressure multiplied by 20, in decibels. The reference sound pressure must be specified. C6 Sound power level (1.44)
soundpowerlevel
The logarithm of the ratio of the sound power to the reference sound power multiplied by 10, in decibels, and the reference sound power must be stated. C7 band sound pressure level (1.47)
bandsoundpressurelevel
refers to the sound pressure level within a limited frequency band. The reference sound pressure and bandwidth must be specified. C8 band sound power level (1.48) band sound power level refers to the sound power level within a limited frequency band. The reference sound power and the bandwidth must be specified. C9 A-weighted sound pressure level A-weighted sound pressure level The sound pressure level measured using an A-weighted network.
C10 Anechoic room (11.19) anechoic room, anechoic chamber, dead room (free-field room) The boundaries effectively absorb all incident sound, making it a room with a basically free sound field. C11 Semi-anechoic room (11.20)
semi-anechoic room
Anechoic room with a reflective floor to simulate a room with semi-free space. C12 Average sound pressure level (12.03)
JB10046-1999
averagesoundpressurelevel,meansoundpressurelevelThe logarithm to the base 10 of the ratio of the spatial or (and) temporal average of the square of the sound pressure of a sound to the square of the reference sound pressure (20μPa) multiplied by 10. The method of averaging the sound should also be indicated. C13 Free field (3.43)
free[sound] field
A sound field in a uniform, isotropic medium in which the influence of boundaries can be ignored.
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